USCG-MASTER100-L2.2

The sail and auxiliary sail endorsement

A Master under 100 GRT is issued for **self-propelled** vessels. If you intend to command a sailing vessel commercially, you need the auxiliary sail endorsement — and the sail charter trade is a large part of why this credential exists at all.

Entry & progression

Optional endorsement. Governing regulation: 46 CFR 11.428.

What it requires

  • 360 days of service on sail or auxiliary sail vessels, per the NMC checklist against 46 CFR 11.428.
  • Plus either the Coast Guard's auxiliary sail examination module, or an approved course in lieu of it.

The 360 days sit inside your total service, not on top of it. Half of the near-coastal Master's 720 days, served under sail, earns the endorsement — you are not being asked for a second career.

Why it is examined separately

A sailing vessel does things a motor vessel does not, and the examination reflects that:

  • She heels, which moves her centre of gravity outboard and changes her stability picture continuously with the wind.
  • She cannot go directly to windward, so passage planning, pilotage and collision avoidance all have to account for tacking.
  • She has right of way over power under Rule 18 — but not when overtaking, not in a narrow channel under Rule 9, and not under Rule 13. Sailing masters who believe otherwise are a recognised hazard.
  • Under sail and power together she is a power-driven vessel — masthead light at night, cone point-down by day.
  • Her rig can fail, and a dismasting alongside is a very different emergency from an engine failure.

WARNING — Sail does not mean right of way Rule 18 gives a sailing vessel priority over a power-driven vessel — except where Rules 9, 10 and 13 otherwise require. A sailing vessel overtaking a motor cruiser gives way. A sailing vessel under 20 m shall not impede a vessel confined to a narrow channel. And a sailing vessel with her engine on is not a sailing vessel at all. Three exceptions, and all three are examined.

Stability under sail

The heeling moment of the rig is the sailing vessel's defining stability problem. Righting moment must exceed heeling moment, and heeling moment climbs with the square of the wind speed — so a gust that doubles the wind quadruples the force on the rig.

Reef early. The decision to shorten sail is always cheaper made ten minutes before you need it than thirty seconds after, and on a vessel carrying passengers who do not know what a knockdown feels like, it is the whole of the job.

Passengers on a heeling boat

A motor vessel that heels ten degrees has a problem. A sailing vessel that heels ten degrees is working normally — and your passengers do not know the difference. They will be frightened by something routine, and unbothered by something that should frighten them.

  • Brief the heel before you leave. Tell them the boat leans, that it is normal, and that you will tell them if anything is wrong.
  • Seat them low and to windward — it is both safer and more comfortable, and it helps your stability rather than hurting it.
  • Watch the leeward rail. A passenger who moves to the low side to look at the water is standing at the point of least freeboard on a heeling boat.
  • Brief the boom. It is at head height, it moves fast, and it is the single most common injury on a sailing charter.

The boom has hurt more paying passengers than the weather ever has. Say the word "gybe" out loud, every time, and mean it.

Practice questions

5 questions
recallcore

recall · core

The auxiliary sail endorsement on a Master under 100 GRT requires: (a) 360 days of service on sail or auxiliary sail vessels, plus an examination module or approved course (b) 720 days on sail vessels (c) No additional service (d) An ocean route endorsement

recallcore

recall · core

A sailing vessel proceeding under sail and power simultaneously is: (a) A sailing vessel, with right of way over power-driven vessels (b) A power-driven vessel, showing a masthead light and a cone point-down (c) A vessel restricted in her ability to manoeuvre (d) Exempt from the Rules

recallcore

recall · core

Rule 18 gives a sailing vessel priority over a power-driven vessel except where: (a) It is at night (b) Rules 9, 10 and 13 otherwise require (c) The power-driven vessel is larger (d) There is no exception

recallcore

recall · core

The heeling moment on a sailing vessel increases with: (a) The wind speed, linearly (b) The square of the wind speed (c) The cube of the wind speed (d) The vessel's length

recallcore

recall · core

The 360 days of sail service required for the endorsement: (a) Are additional to the total service required for the credential (b) Sit within the total service required for the credential (c) Must all be on ocean waters (d) Must all be as master

AI-drafted catalogue content pending SME review. USCG requirements change; verify every figure against the National Maritime Center and the current CFR before relying on it for an application.

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